Engineers are constantly looking for ways to improve the efficiency and performance of internal combustion engines. Several conflicting demands on some engines have placed undesirable spacial limitations relating to the intake and exhaust valve(s) as well as the incorporation of a suitable fuel injection system. In many diesel type engines, four gas exchange valves (two intake and two exhaust) surround a centrally mounted fuel injector whose tip protrudes directly into the hollow piston cylinder. Because manufacturing constraints generally restrict each of the valves and fuel injectors to a circular cross section, the size of these components is limited by each other and the size of the piston for a given engine. These spacial constraints often result in compromises between the valves and fuel injector that result in an engine with less efficiency and lower performance levels than should otherwise be possible.
In many engines, both the gas exchange valve(s) and the fuel injection system are coupled in their operation to the crank shaft angle of the engine. In other words, in many engines these components are driven to operate by a rotating cam that is driven to rotate directly by the engine. Engineers have recognized that combustion efficiency and overall engine performance can be improved by de-coupling the operation of the fuel injection system from the rotation angle of the engine. In this regard, Caterpillar, Inc. of Peoria, Ill. has seen considerable success by incorporating hydraulically-actuated electronically-controlled fuel injectors into engines. These fuel injection systems allow an engine computer to inject a calculated amount of fuel, often in a pre-determined way, into the combustion space in a timing that is based upon sensed operating conditions and other parameters.
In part because of the gains observed by the incorporation of hydraulically-actuated electronically-controlled fuel injectors, engineers believe that further improvements in performance and efficiency can be gained by also de-coupling the gas exchange valves from the engine rotation angle. In other words, it is also desirable that the gas exchange valves be electronically-controlled in order to control exhaust and intake portions of the engine cycle independent of the engine crank shaft angle. This could allow the intake and exhaust portions of the engine cycle to be optimized for a particular operating condition and other parameters, such as temperatures and pressures, etc.
The present invention is directed to overcoming these and other problems, as well as improving the efficiency and performance of engines in general.